There have been several attempts to provide liquid detergent compositions that could have bleach-type components or additives. However, the most stable compositions have often had certain problems including dissolution problems, or uneven distribution or application of the components or additives. There have also been problems in many compositions of the prior art in that they could not provide long term stability without some significant phase separation of the solid and liquid components.
Some of the various patents related to liquid detergent compositions are listed below. Patent Applications 293 040 and 294 904, describe aqueous detergent compositions having a pH above 8 containing an anionic surfactant at conventional levels, i.e. above 5% by weight, typically from 15% to 40% by weight, and a solid, water-soluble peroxygen bleach dispersed in a specific water/solvent liquid phase.
EP-A-0 328 182 discloses liquid laundry detergent and fabric softener compositions containing a Smectite-type clay fabric softener and an antisettling agent in a low water/polyol formulation, and optionally, a polymeric clay-flocculating agent.
EP-A-0 110 472 discloses an aqueous liquid detergent composition comprising conventional detergent ingredients and from 1-10% by weight of silica with a surface area of greater than 200 m.sup.2 /g.
U.S. Pat. No. 4,075,118 discloses concentrated, low-sudsing liquid detergent compositions containing a mixture of nonionic surfactants, anionic surfactants and a self-emulsified silicone suds controlling agent.
EP-A-O 124 143 discloses a process for the preparation of a neutral or low-alkaline silica-containing aqueous liquid detergent composition, comprising detergent-active material and detergency builder, characterized by the step of admixing particulate alkalimetal silicate into the aqueous base at a temperature of below 50.degree. C.
EP-A-9 839 discloses examples of some bleach compositions based on hydrogen peroxide which are well-known; such compositions are mainly used for hard-surface cleaning applications, and are not desirable for use during the washing cycle of a washing machine. Their drawbacks include low solution pH and therefore poor efficiency, and high level of free hydrogen peroxide in the product, not desirable for consumer safety reasons.
There is, therefore, a need for liquid detergent compositions containing bleach, suitable for use in washing machines, which do not have the dissolution, stability or phase separation problems of the prior art, and which, once added to the wash medium, can be immediately effective on the fabrics.
It has now been surprisingly found that stable liquid detergent compositions with bleach, having suspended solid peroxygen compound, can be formulated with hydrophobic silica, without impairing the chemical stability of the composition and while enhancing the physical stability of the composition. The present invention therefore answers the above-mentioned need, by providing liquid detergent compositions with bleach, containing solid peroxygen compound, which are stable upon storage, show excellent viscosity/pourability characteristics, and dissolve quickly and efficiently in the wash medium.
The present compositions, which exhibit an alkaline pH, allow one to obtain an optimal performance from the bleach component.